Support MOSS-TTSD v0.7 fused with codec

[CloudRipple]

Motivation

This pull request introduces support for multi-channel audio generation models, specifically adding configuration and runtime changes for Moss-TTSD-With-Codec. Key enhancements include new model configuration, improved handling of multi-channel input/output, and sampler logic updates to support multi-channel generation. The changes are grouped below by theme:

Modifications

Multi-channel audio model support:

• Added MossTTSDWithCodecConfig in python/sglang/srt/configs/moss_ttsd_with_codec.py and registered it in python/sglang/srt/configs/__init__.py to support Moss-TTSD-With-Codec audio generation models. [1] [2] [3]
• Introduced _init_channels method and related logic in ModelConfig to normalize and handle multi-channel metadata from model configs (channels or n_vq). [1] [2]
• Added is_audio_gen_model utility and detection logic for audio generation models, updating model type checks and health endpoints. [1] [2] [3]

Input/output handling for multi-channel models:

• Updated generate API in engine.py to accept nested lists for input_ids and propagate multi_channel flag. [1] [2]
• Enhanced replay logic in NPU graph runner to handle lists of outputs for multi-channel inference.

Sampler logic improvements:

• Introduced MultiChannelSampler class in sampler.py to handle sampling for multi-channel logits, and updated create_sampler to select the appropriate sampler based on multi_channel flag. [1] [2]
• Modified LogitsProcessor and its buffer copying logic to handle per-channel vocab sizes and output slicing for multi-channel models. [1] [2]

Miscellaneous:

• Minor import fix in sampler.py and added tempfile import in detokenizer_manager.py. [1] [2]

Accuracy Tests

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.